diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 7bbb3c2f7..2431e9fb1 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -44,7 +44,7 @@ static void bailout(TokenList *tokenlist, ErrorLogger *errorLogger, const Token
     errorLogger->reportErr(errmsg);
 }
 
-static bool bailoutFunctionPar(const Token *tok)
+static bool bailoutFunctionPar(const Token *tok, const ValueFlow::Value &value, const Settings *settings)
 {
     // passing variable to subfunction?
     const bool addr = tok && Token::Match(tok->previous(), "&");
@@ -64,8 +64,11 @@ static bool bailoutFunctionPar(const Token *tok)
     if (!Token::Match(tok,"%var% ("))
         return false; // not a function => dont bailout
 
-    if (!tok->function())
-        return true; // unknown function bailout
+    if (!tok->function()) {
+        // unknown function.. bailout unless value is 0 and the library
+        // says 0 is invalid
+        return (value.intvalue!=0 || !settings->library.isnullargbad(tok->str(), 1+argnr));
+    }
 
     const Variable *arg = tok->function()->getArgumentVar(argnr);
 
@@ -210,7 +213,7 @@ static void valueFlowBeforeCondition(TokenList *tokenlist, ErrorLogger *errorLog
                 }
 
                 // assigned by subfunction?
-                if (bailoutFunctionPar(tok2)) {
+                if (bailoutFunctionPar(tok2,val2.condition ? val2 : val,settings)) {
                     if (settings->debugwarnings)
                         bailout(tokenlist, errorLogger, tok2, "possible assignment of " + tok2->str() + " by subfunction");
                     break;
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index 076b3016a..787e9c642 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -43,6 +43,13 @@ private:
         Settings settings;
         settings.valueFlow = true;  // temporary flag
 
+        // strcpy cfg
+        const char cfg[] = "<?xml version=\"1.0\"?>\n"
+                           "<def>\n"
+                           "  <function name=\"strcpy\"> <arg nr=\"1\"><not-null/></arg> </function>\n"
+                           "</def>";
+        settings.library.loadxmldata(cfg, sizeof(cfg));
+
         // Tokenize..
         Tokenizer tokenizer(&settings, this);
         std::istringstream istr(code);
@@ -143,6 +150,12 @@ private:
         ASSERT_EQUALS(false, testValueOfX(std::string("void setx(int &x);")+code, 2U, 1));
         ASSERT_EQUALS(false, testValueOfX(code, 2U, 1));
 
+        code = "void f(char* x) {\n"
+               "  strcpy(x,\"abc\");\n"
+               "  if (x) {}\n"
+               "}";
+        ASSERT_EQUALS(true, testValueOfX(code, 2U, 0));
+
         // while, for, do-while
         code = "void f(int x) {\n" // loop condition, x is not assigned inside loop => use condition
                "  a = x;\n"  // x can be 37